1. Field of the Invention
The invention relates to an intraocular lens implant device for placement within the human eye for restoration of vision after the removal of an extra capsular cataract.
2. Description of the Prior Art
There have been many different intraocular lens designs and styles which incorporate and rely upon on many different principles and methods for fixation within the eye. The first modern intraocular lens implanted in 1949 by Mr. Ridley was placed within the capsular bag and relied on posterior capsular fixation, peripherally, for support. Additional support was obtained by iridocapsular adhesions which developed naturally postoperatively as a result of the inflammation produced by the cataract surgery. The problem with this particular design, however, was that fixation was unreliable since the iridocapsular adhesions were unpredictable in their development postoperatively.
Since this first implant design, many other fixation principles have been utilized including:
1. Anterior chamber angle fixation. PA1 2. Pupillary support. PA1 3. Iris Fixation PA1 4. Iridocapsular fixation PA1 5. Scleral fixation
A. Iris suture PA2 B. Iris clip PA2 A. Anterior chamber Posterior Chamber PA2 B. Ciliary sulcus fixation--Shearing style PA2 C. Capsular bag fixation
In the anterior chamber design, fixation is accomplished by peripheral haptic members that extend into the angle of the anterior. The iris clip and iris suturing techniques employ the use of a clip or iris suture to hold the implant to the iris.
In the posterior chamber, ciliary sulcus fixation is accomplished again by a peripheral haptic member which extends beyond the optic, and accomplishes fixation by contacting the peripheral tissues of the eye posterior to the iris in the area of the ciliary sulcus.
Posterior chamber fixation within the capsular bag is accomplished by several implant designs. All of the designs require haptic members which extend peripherally from the optic into the capsular cul-de-sac and thereby hold the implant in place. Sometimes adhesions develop in the area of the "cul-de-sac", where the anterior capsular surface curves around its equatorial transition to become the posterior capsule. Some designs simply wedge themselves into position in this peripheral capsular cul-de-sac and, in fact, never develop true adhesions, and are simply fixated by physical pressure in the peripheral capsular cul-de-sac. Other implant designs are held in position by adhesions developing between the anterior and posterior capsule around the peripheral haptic member. In most cases, it is felt that no true adhesion develops between the haptic and the capsule itself or the optic in the capsule itself, but that the implant is fixated and held in position due to capsular adhesions developing between the anterior and posterior capsules, these adhesions developing around, but not onto, the peripheral fixation members. This lack of adhesions directly to the peripheral haptic member is evidenced also by the relatively easy removal of many implants, the haptics of which can slide through tunnels composed of surrounding adhesive tissue.
In one particular design, the posterior surface of the "wings" peripheral to the central optic have been roughened to produce an opacifiction of these "wing" portions of the lens adjacent to the central optic. This is to eliminate glare from the optic edge. It has been claimed that this style fixates well not only due to peripheral haptic adhesions within the capsular bag, but possibly due also to capillarity or adhesions developing between the roughened posterior surface of the optic "wings".
As mentioned, all of the above designs within the capsular bag are dependent upon either biologically developing capsular adhesions around peripheral haptics, or the implant is held in place by wedging itself into the peripheral capsular cul-de-sac. It would be a considerably improvement in implant design if a mechanism for fixating the implant could be obtained while eliminating the need for peripheral haptic members. This would allow for a smaller sized implant, which would be more easily implantable through a smaller incision, and would also minimize ocular irritation after implantation.